Human exposure to phthalates is ubiquitous. Esters of phthalic acid are widely used as plasticizers for many types of plastic ranging from polyvinyl chloride to food wraps, toys and building products. Recent evidence suggests that environmental phthalate exposure adversely impact pregnancy outcome in humans. The objective of this project is to test the hypothesis that maternal exposure to phthalates early in pregnancy has an adverse effect on pregnancy outcome. The subject population is a cohort of 1500 low income, minority pregnant women from Camden, New Jersey. Maternal excretion of phthalate metabolites in urine and plasma early and late in pregnancy will be measured by isotope ratio gas chromatography mass spectrometry with selective ion monitoring. Outcomes of interest include preterm delivery (<37 weeks) and very preterm (<32 weeks), low birthweight (<2500 g), fetal growth restriction (<10 percentile of standard), gestation duration together with the incidence of birth defects, particularly male urogenital defects including cryptorchidism and hypospadias. All of the necessary samples along with subject data, prospective biological samples and pregnancy outcomes are in hand for the cohort. Preterm delivery, the leading cause of infant morbidity and mortality in the United States, has increased by 30% during the past 2 decades for reasons that are unknown. Risk is highest for low income minorities who may also have increased exposure to environmental pollutants like phthalate. Relevance: It is now generally accepted that chemicals introduced into the environment by human activity have adverse effects on human health. This study will provide information on the effects of maternal phthalate exposure to pregnancy outcome. The findings will have immediate ramifications for public health, for the packaging trade and for the chemical industry. PUBLIC HEALTH RELEVANCE: Human exposure to phthalates is ubiquitous. Esters of phthalic acid are widely used as plasticizers for many types of plastic used for food wraps, toys and building products. Recent evidence suggests that environmental phthalate exposure adversely impact pregnancy outcome in humans. The objective of this project is to test the hypothesis that maternal exposure to phthalates early in pregnancy has an adverse effect on pregnancy outcome. The findings will have ramifications for public health, for the packaging trade and for the chemical industry.